Indexing fluid control device

ABSTRACT

A fluid control device which shifts to alternate positions in response to successive applications and removals of signal pressure. The device uses no mechanical latches and has only a single bore and spool. It can be used with compressible or incompressible fluids, and avoids entrapment of entrained fluid particles when compressible fluids are used by an automatic venting arrangement for the spool end chambers.

United States Patent Porter, Sr. [4 1 Jan. 18, 1972 [5 INDEXING FLUID CONTROL DEVICE 1 References Cited ['72] Inventor: Edward B. Porter, Sn, Pontiac, Mich. UNITED STATES PATENTS [73] Assignee: Ross Operating Valve Company, Detroit, 3,459,224 8/1969 Weber l37/625.63

Mich.

Primary ExaminerHenry T. Klinksiek [22] Filed 1970 Attorney-Hamess, Dickey & Pierce [21] App]. No.: 65,960

[57] ABSTRACT A fluid control device which shifts to alternate positions in [52] U.S.Cl ..l37/625.63 response to Successive applications and removals of Signal [51] Int Cl u 11/07 pressure. The device uses no mechanical latches and has only [58] Field of Search 62563 62556 a single bore and spool. It can be used with compressible or in- M2554 compressible fluids, and avoids entrapment of entrained fluid particles when compressible fluids are used by an automatic venting arrangement for the spool end chambers.

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INDEXING FLUID CONTROL DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to fluid control devices. and more particularly to devices shiftable between two alternate positions in response to application and removal of signal pressure. The device is usable with compressible or incompressible fluids.

2. Description of the Prior Art The prior art is exemplified by Brinkel US. Pat. No. 2,921,602 issued Jan. 19, 1960 and Weber US. Pat. No. 3,459,224 issued Aug. 5, 1969. These devices are shiftable from one position to the other in response to the successive application and removal of signal pressure, being returnable to the first position upon the second application and removal of the signal. The Brinkel patent has two bores with spools mounted therein and with a mechanical latch interconnecting the spools. Figures and 11 of this patent show modifications usable with incompressible fluids.

The Weber patent was an improvement on the Brinkel construction in that only a single spool and bore are used and no mechanical latch is needed, the valve being held in its positions by means of differential areas provided on the spool. However this device is not usable with incompressible fluids and furthermore, its use with compressible fluids is hampered by the fact that entrained liquid particles such as lubricant tends to accumulate in the end chambers. The volume of the cavities forming the end chambers must also be large enough to prevent any slowing down of valve movement, since the air is trapped in the end chambers as the valve moves toward them. Factors such as these have made the unit shown in the Weber patent unsatisfactory in certain applications.

BRIEF SUMMARY OF THE INVENTION The present invention retains the, advantages of the Weber patent over the previous Brinkel construction, that is, elimination of the mechanical latching means and a more economical single bore construction. At the same time it permits the unit to use compressible or incompressible fluids and enables it to operate without accumulating entrained liquid particles such as lubricant when a compressible fluid is used. The invention also eliminates any problem with slowness of operation when the valve shifts between positions by avoiding entrapment of fluid in the end chambers.

According to the invention, a pair of vent valves are provided at the end chambers which are automatically opened in alternate fashion as the spool approaches each end chamber. As a result the fluid, which is fed into each end chamber twice during the complete cycle from one direction, is immediately vented out of the chamber in the same direction to exhaust. Thus, there is no resistance to spool movement, and the alternate ebb and flow to and from the end chambers which occurred twice during each flow cycle in the previous Weber device is eliminated. Instead, the fluid flow is always in the same direction through the end chambers to keep them from accumulating any entrained liquid particles. The automatic venting of the end chambers also permits incompressible fluids to be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional and partly schematic view of the invention showing the spool in one position with both the output and signal ports exhausted, both vent valves being closed;

FIG. 1A is a view similar to FIG. I but with the signal port pressurized and the spool moving rightward toward a position pressurizing the output port, this view showing one of the vent valves opened so that the adjacent end chamber is being vented;

FIG. 2 is a view similar to FIG. I but showing the spool in its final position with the output port pressurized;

FIG. 3 is a view similar to FIG. 2 but showing the signal port exhausted with both vent valves being closed; and

FIG. 4 is a view similar to FIG. 3 but showing the spool shifted leftward back to its first position, the signal port being pressurized and the output port exhausted, the second vent valve being in its open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The first portion of this description is similar to the description of the Weber unit in US. Pat. No. 3,459,224. The adapter is generally indicated at 11 and comprises a body I2 which may be shaped so as to be mountable in an assembly, such as between a solenoid-operated pilot valve I3 and a fluidoperated motor 14. These are shown schematically in FIG. I, valve 13 being controllable by a solenoid 15 which when energized, for example, will supply fluid pressure from a supply port 16 to a signal line 17. When solenoid I5 is deenergized, signal line I7 will be connected to an exhaust port 18. Motor 14 has a chamber 19 supplied by a port 21 so as to actuate a piston rod 22 which may, for example, operate a main valve.

The object of the fluid control device is to alternately pressurize and exhaust motor chamber 19 upon successive pulsations in the signal line 17. For example, starting from an initial condition in which signal line 17 is exhausted and chamber 19 is also exhausted, piston rod 22 will be lifted by a spring 23. A signal pulse applied to line 17, for example, by closure of a switch 24 in the circuit of solenoid 15, will cause pressurization of chamber 19 and downward movement of the piston rod. Removal of the pressure signal pulse from line 17, by opening of switch 24, will still leave chamber 19 pressurized and piston rod 22 depressed. This release of the signal pulse may occur immediately after its application, since the closure of switch 24 may be momentary. However, the next closure of switch 24 and application of pressure in signal line 17 will result in exhaustion of chamber 19 and retraction of piston rod 22. The next exhaustion of signal line 17 will leave chamber 19 exhausted and piston rod 22 lifted. The cycle would then be repeated.

Body 12 has a bore generally indicated at 25 which is closed at its opposite ends by covers 26 and 27. A pair of cup-shaped members 28 and 29 are secured within bore 25 by covers 26 and 27 respectively. A spool generally indicated at 31 is slidably disposed within bore 25 and within chambers 32 and 33 formed by members 28 and 29 respectively. This spool has a bore 34 within which is secured a pair of hollow cylindrical inserts 35 and 36. The inserts are spaced from each other and are flush with the ends of the spool. A shuttle valve 37 is disposed in the space between the inserts, this shuttle being cylindrical in shape and shorter than the distance between the inserts. A pair of similar helical coil compression springs 38 and 39 of equal unstressed length are disposed within inserts 35 and 36 respectively. One end of each spring engaging the shuttle and the other end a member 28 or 29. The shuttle is movable between a first position (FIG. I) engaging a seal 41 on insert 35 in a second position (FIG. 3) engaging a seal 42 on insert 36.

A supply port 43 in body 12 is connected with a chamber 44 adjacent member 28 and which forms an enlargement of bore 25. Reference numeral 43 indicates an internal supply port, while an alternately usable external supply port is indicated at 43a. Spool 3Ihas a seal 45 slidable within chamber 32 and another seal 46 of larger diameter slidable within bore 25 when the spool is in the position of FIG. 1 or 4. In the position of FIGS. 2 and 3 seal 46 is within the enlarged chamber 44. However, in the FIG. 1 or FIG. 4 position, the pressure from supply port 43 will act in opposite directions against seals 45 and 46, and since the latter has a larger diameter there will be a force differential tending to urge spool 31 leftwardly in the FIGS.

An exhaust port 47 is also provided in body 12, this port being connected with a chamber 48 formed in bore 25 adjacent member 29 when spool 31 is in the position of FIGS. 1 or 4. Spool 31 carries a seal 49 which, in the position of FIG. 2 or 3, engages a land 51 of bore 25 having a larger diameter than that which engages seal 46. Seal 49, when in this position, will separate chamber 48 from exhaust port 47. However, at this time, supply chamber 44 will be connected with the narrower portion of bore from which seal 46 has been withdrawn. This narrower portion is indicated at 52 in FIG. 2.

A seal 50 is carried by the end of spool 31 within chamber 33. The area of this seal is equal to that of seal 45 but is greater than the area differential between seals 45 and 46, for purposes which will hereafter appear.

An output connection 53 of adapter 11 is connected to port 21 of motor 14, this output connection having' two ports indicated at 54 and 55 in FIG. 2. Port 54 is connected with bore portion 52 while port 55 is connected with chamber 48. It will thus be seen that, for example, in the FIG. 1 position port 55 will be connected to exhaust port 47 while in the FIG. 2 position port 54 will be connected with supply port 43. Therefore, when moving to the FIG. 2 position, adapter 11 will change motor chamber 19 from an exhaust condition to a supply condition.

Signal line 17 is connected to a signal port 56 in bore portion 52 adjacent a reduced portion '57 of spool 31. This reduced section is bounded by a pair of seals 58 and 59, and radial passages 61 (FIG. 2) are formed in the spool and connect the signal port 56 with bore 34 adjacent shuttle 37.

It should be noted that the area of seal 49 is greater than the area of seal 58 or 59. When the spool is in the FIG. 3 position, as will later be described in detail, supply pressure will be acting on the area of seal 49 urging it rightwardly and on the area of seal 58 urging it leftwardly so that the force differential will retain the spool in the FIG. 3 position. The area of seal 45 however is greater than the difference between the area of seals 49 and 58; therefore, pressurization of chamber 32 will move the spool leftwardly to the FIG. 4 position.

The operation of the unit as thus far described is as follows: assuming an initial position of the parts as shown in Figure l, chamber 32, which is not being supplied at this time, will be exhausted via bore 62 of member 35 and passages 61 leading to signal port 56. Spring 39 has insufficient force to maintain shuttle 37 against seal 41 against the pressure in chamber 32.

Output connection 53 will be exhausted through port 55, chamber 48 and exhaust port 47. The spool will be held or latched in the position shown by a force equal to the area differential of seals 46 and 45 times the fluid pressure. These are the only two seals which will be active in the position shown in FIG. 1.

FIG. 2 shows the position of the parts after signal port 56 has been pressurized. Shuttle 37 will be forced against seal 41 to close off the passage leading to chamber 32. Chamber 33 will be pressurized via passages 61 and 63, the latter being within member 36. The spool will move to the rightward position, since the area of seal 50 is greater than the area of seal 46 less the area of seal 45. During the first portion of this rightward movement the force created by the differential areas between seals 46 and 45 will tend to oppose spool movement, that is, it will tend to counteract the shifting force. Therefore, the latter must build up to a substantial level before movement begins. Once the movement does begin, seal 46 will be withdrawn from bore 52, thereby releasing the latching force and, in effect, assisting movement during the last portion of spool travel.

Movement to the FIG. 2 position will cause output connection 53 to be pressurized, since supply pressure from chamber 44 will flow through bore 52 into output port 54, while seal 49 enters land 51 to separate port 55 from exhaust port 47.

When signal port 56 is exhausted, the parts will assume their FIG. 3 position. Spool 31 will remain in its rightward position but shuttle 37 will shift away from seal 41 and against seal 42, as urged by spring 38 which is compressed more than spring 39. This is because chamber 33 will be exhausted via passages 63 and 61 to the signal port. Spring 38 is of insufficient force to maintain the pressure in chamber 33.

Output connection 53 will remain pressurized due to the connection between supply port 43 and output port 54 described above. The spool will be held or latched" in the position shown in FIG. 3 by a force equal to the differential area between seals 49 and 58 times the supply pressure. This will come about as follows: Chamber 48 will have supply pressure obtained from output connection 53 and port 55. This will urge spool 31 rightwardly. Smaller seal 58 will be exposed to supply pressure from the right, urging the spool leftwardly but with a lesser force. The supply pressure acting on seal 45 in a rightward direction will be counterbalanced by the pressure acting on seal 50 in a leftward direction, since these two seals are of identical area.

Upon the next pressurization of signal port 56, chamber 32 will be pressurized via passages 61 and 62. Spool 31 will be moved to its leftward position since the area of seal 45 is greater than the area of seal 49 minus the area of seal 58. As before, there will be an initial force counteracting the shifting force so that the pressure in chamber 32 must build up to a substantial level before movement begins. However, once it does begin, seal 49 will become separated from land 51 and chamber 48 will be connected to exhaust port 47. This will remove the latching or restraining force and as seal 46 engages bore portion 52 the new latching force will take effect.

The movement to the FIG. 4 position will also exhaust output connection 53 past seal 49. Shuttle 37 will remain in its leftward position against seal 56 so that the fluid pressurizing chamber 32 cannot escape.

Removal of signal port pressure will cause the parts to shift from the FIG. 4 to the FIG. 1 position. That is, spool 31 will remain in its leftward position, exhausting output connection 53, but the removal of pressure against shuttle 37 will permit spring 39 to move the shuttle to its rightward position as shown in FIG. 1. The parts will then be ready for a repetition of the cycle.

In order to accomplish the objects of the invention as above stated, chambers 32 and 33 are provided with vent valves.

generally indicated at 64 and 65 respectively. Theses vent valves are of the poppet type and operate in chambers 66 and 67 which are connected to chambers 32 and 33 respectively by passages 68 in cup-shaped members 28 and 29. Inserts 69 and 71 are disposed between the cover plates and their adjacent members 28 or 29, and these inserts carry the seats 72 for the vent valves. These vent valves have pistons 73 and 74 riding in inserts 69 and 71 respectively, the pistons forming chambers 75 and 76 and having a larger effective area than valve seats 72. When either vent valve is open, it will permit fluid to flow from its respective chamber 66 or 67 through a chamber 77 under its piston to an exhaust passage 78 in body 12 by means of passages 79 in inserts 69 and 71, passage 78 being connected to exhaust port 47.

Chamber 66 is connected with piston chamber 76 of vent valve 65, while chamber 67 is connected to piston chamber 75 of vent valve 64. These connections are made by passages 81 and 82 respectively in body 12 and by appropriate passages 83 in members 28 and 29. The vent valves are normally urged to their closed position by springs 84. When chamber 66 is pressurized (simultaneously with chamber 32) it will lift vent valve 65 off its seat, venting chambers 33 and 67. Similarly, when chamber 67 is pressurized (simultaneously with chamber 33) it will cause vent valve 64 to lift off its seat, venting chambers 32 and 66. The result is that the end chambers will automatically be vented as soon as spool 31 moves toward them, and the fluid will flow out of each chamber in the same direction that it flowed in, so that there will be no ebb and flow of fluid in the chambers.

The operation of the invention may best be illustrated with respect to FIG. 1A which shows an intermediate position between FIGS. 1 and 2 after chambers 33 and 67 have been pressurized but before output port 53 has been opened. As will be seen, the pressure from chamber 67 conducted through passage 82 will pressurize piston chamber 75 of vent valve 64, lifting the valve off its seat and permitting fluid to flow from chambers 32 and 66 past the vent valve and into chamber 77 and passages 79 and 78 to exhaust port 47. At the same time 67, also exhausting piston chamber 75 and permitting spring 84 to return vent valve 64 to its closed position. The pressurization of chambers 32 and 66 by the next application of signal pressure will immediately pressurize piston chamber 76 through passage 81, lifting vent valve 65 from its seat. Thus,

the fluid displaced from chambers 33 and 67 as spool 3i moves to the left (its FIG. 4 position) will be vented out through passage 78 to exhaust port 47. Removal of the second signal pulse will permit return of vent valve 6'5 to its FlG. ll position.

Should a compressible fluid such as air or gas be used, any entrained liquid particles such as lubricant which remain in any of the end chambers will not accumulate in these chambets but will be forced by the spool past the vent valves to the exhaust port, thus preventing undesired liquid accumulation, The automatic venting will also avoid any possibility of slowdown in spool movement which might otherwise occur.

What is claimed is:

1. In combination, an actuating spool shiftable between first and second positions, first and second chambers pressurizable to shift said spool respectively to said first and second positions, a central chamber, means for alternatively pressurizing and exhausting said central chamber, passageway means connecting said central chamber with said first and said second chambers, valve means disposed in said passageway means and movable between a first position preventing fluid flow to said first chamber and a second position preventing fluid flow to said second chamber, means responsive to movement of said spool to said first and second positions for urging said valve means toward its first and second positions, respectively, a constantly pressurized supply port, a first pair of seals on said spool having different areas, opposite sides of said seals being connected to said supply port in response to movement of said actuating spool to its first position, whereby the differential force created by said different areas tends to hold said spool in said first position, a second pair of seals on said spool having different areas, opposite sides of said last-mentioned seals being connected to said supply port in response to movement of said actuating spool to its second position, whereby the differential force created by said last-mentioned different areas tends to hold said spool in said second position, a vent valve for each of said first and second chambers, each vent valve being held closed in response to pressure in its chamber, means responsive to pressure in said second chamber for opening the vent valve for said first chamber, means responsive to pressure in said first chamber for opening the vent valve for said second chamber, and passageways leading fluid flowing past each of said vent valves to exhaust.

2. The combination according to claim ll, said vent valves being of the poppet type and having springs holding them normally closed.

3. The combination according to claim 1, said means for operating said vent valves comprising pistons forming piston chambers.

4. The combination according to claim 3, said vent valves being aligned with said spool at the opposite ends thereof and being of the poppet type, and springs holding said vent valves normally closed. 

1. In combination, an actuating spool shiftable between first and second positions, first and second chambers pressurizable to shift said spool respectively to said first and second positions, a central chamber, means for alternatively pressurizing and exhausting said central chamber, passageway means connecting said central chamber with said first and said second chambers, valve means disposed in said passageway means and movable between a first position preventing fluid flow to said first chamber and a second position preventing fluid flow to said second chamber, means responsive to movement of said spool to said first and second positions for urging said valve means toward its first and second positions, respectively, a constantly pressurized supply port, a first pair of seals on said spool having different areas, opposite sides of said seals being connected to said supply port in response to movement of said actuating spool to its first position, whereby the differential force created by said different areas tends to hold said spool in said first position, a second pair of seals on said spool having different areas, opposite sides of said last-mentioned seals being connected to said supply port in response to moVement of said actuating spool to its second position, whereby the differential force created by said last-mentioned different areas tends to hold said spool in said second position, a vent valve for each of said first and second chambers, each vent valve being held closed in response to pressure in its chamber, means responsive to pressure in said second chamber for opening the vent valve for said first chamber, means responsive to pressure in said first chamber for opening the vent valve for said second chamber, and passageways leading fluid flowing past each of said vent valves to exhaust.
 2. The combination according to claim 1, said vent valves being of the poppet type and having springs holding them normally closed.
 3. The combination according to claim 1, said means for operating said vent valves comprising pistons forming piston chambers.
 4. The combination according to claim 3, said vent valves being aligned with said spool at the opposite ends thereof and being of the poppet type, and springs holding said vent valves normally closed. 